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The expansion joint that separates my garage from the driveway has a 1x4 board that is mostly rotted and I have pulled some of it up. I would like to fill this 3/4 to 1" gap with something heavy duty like what they use on city streets to fill the cracks. Home depot has some stuff in a small 1 liter bottle that might work but it is about 15 bucks for one and it would take probably 30of them to fill the length of the gap. Does anyone have any ideas that of a product that is fairly cheap that would work for this.

Looking forward to replies on this one. This past weekend cleaned out gap on my drieveway concrete and there's about 1" gap for maybe 12 ft and 3" deep. Mine might take several gallons to fill.

Could I fill most of void with thick tar so nothing would grow back in there, and then top off with say 1" of better flexible fill product?

Thats about the same as what I got. I have 30 feet to fill that's about 3 to 4 in deep and about 3/4 to 1" wide gap. I thought about filling most of it with some backer rod and then filling the top with some kind of heavy duty filler.

The stuff on the streets is not much more than roofing tar. Maybe for a twenty a roofer will pour you out some. It will stay hot for about 20-30 minutes in a metal pail. It's nearly 500 º so be extra careful.

Dig out the old expansion material, back fill most of crack with sand, spray generously with weed killer, push in 3/4" backer rod, fill with sikaflex or the Qikcrete crack fill from HD or Lowes. Did this at the end of my drive 3 years ago and still holding up after driving on it daily, shoveling snow and a using a snow blower. Use on a warmer day and the crack fill should self level.

Filled my driveway expansion joint with sikaflex after using sand and backer rod to take up most of the joint. The joint is 3/4 to 1in. wide. Sikaflex is some really cool stuff. Here are some pics right after I was done.

I trick I learned is used clear dish soap on your fingers to smooth it out. Kind of like spitting on your finger with caulk. But the soap works wonders

As for its strength, I've ripped out porches and had just the sikaflex hold a piece of concrete to the house.

This is the way, best done at the time the concrete is poured. Other brand are available, look for self leveling urethane.

When I put in my drive 25 years ago, I specked this to the contractor. They were unfamiliar with it and complained why I wanted it. After they used it they started selling it on all of their commercial work and would bring customers to my home for a inspection. With new work there is available a plastic cap strip that fits over the top of the normal felt that installed in the expansion joint. Once the pour is complete and the forms are removed, you peel off the top 1/2" of the cap and you have a perfect 1/2 * 1/2 recess to apply the urethane.

One other thing I learned later was to do the saw cut control joints too. After about 5 years one saw cut section of a slab started to heave up from the frost, water leaking in the cut and freezing. I used 1/4" backer rod to fill all of the cuts and applied the urethane, making sure that the cuts were well cleaned to ensure bonding to the slabs.

After all these years my 60 yards of drive is still in great shape, no further slab movements, and no weeds to kill in the joints. If your in snow shovel country, don't fill all the way to the top, to prevent hitting it with a shovel or snow-thrower.

One other tip, if you can't find backer rod to fill the gap you have because it's too big. Buy some foam pipe insulation and cut it lengthwise to fit. As I recall the urethane is only supposed to be 1/2" deep.

MTW The foam pipe insulation would have been a great idea. I needed 1" backer rod and couldn't find any place close to me that had any so I had to order it from amazon. Had I thought of the pipe insulation I would have went that route.

And you are right about the 1/2in depth. That's the MAX that they recommend.

I went to bestmaterials.com to get my backer rod. They have closed-cell and soft-cell in varying widths. I used their NovaLink SL and have been pretty pleased so far. On a side note, I used play sand 6 years ago to fill that gap and topped with a DAP concrete filler. DAP stuff held up, but I would not do the sand fill again. We ended up with a huge ant colony, thousands of ants! If you go that route I would pour diesel fuel or something on top of the sand to discourage the ants. Maybe not the most EPA friendly thing to do, but beats the alternative.